<!DOCTYPE HTML>
<html lang="zh-CN">


<head>
    <meta charset="utf-8">
    <meta name="keywords" content="DDD领域层的一些设计规范, 戴某的博客">
    <meta name="description" content="戴某的笔记">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=no">
    <meta name="renderer" content="webkit|ie-stand|ie-comp">
    <meta name="mobile-web-app-capable" content="yes">
    <meta name="format-detection" content="telephone=no">
    <meta name="apple-mobile-web-app-capable" content="yes">
    <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
    <!-- Global site tag (gtag.js) - Google Analytics -->


    <title>DDD领域层的一些设计规范 | 戴某的博客</title>
    <link rel="icon" type="image/png" href="/dai_modest/favicon.png">

    <link rel="stylesheet" type="text/css" href="/dai_modest/libs/awesome/css/all.css">
    <link rel="stylesheet" type="text/css" href="/dai_modest/libs/materialize/materialize.min.css">
    <link rel="stylesheet" type="text/css" href="/dai_modest/libs/aos/aos.css">
    <link rel="stylesheet" type="text/css" href="/dai_modest/libs/animate/animate.min.css">
    <link rel="stylesheet" type="text/css" href="/dai_modest/libs/lightGallery/css/lightgallery.min.css">
    <link rel="stylesheet" type="text/css" href="/dai_modest/css/matery.css">
    <link rel="stylesheet" type="text/css" href="/dai_modest/css/my.css">

    <script src="/dai_modest/libs/jquery/jquery.min.js"></script>

<meta name="generator" content="Hexo 5.4.0"><link rel="alternate" href="/dai_modest/atom.xml" title="戴某的博客" type="application/atom+xml">
<link rel="stylesheet" href="/dai_modest/css/prism-tomorrow.css" type="text/css"></head>



   <style>
    body{
       background-image: url(https://cdn.jsdelivr.net/gh/Tokisaki-Galaxy/res/site/medias/background.jpg);
       background-repeat:no-repeat;
       background-size:cover;
       background-attachment:fixed;
    }
</style>



<body>
    <header class="navbar-fixed">
    <nav id="headNav" class="bg-color nav-transparent">
        <div id="navContainer" class="nav-wrapper container">
            <div class="brand-logo">
                <a href="/dai_modest/" class="waves-effect waves-light">
                    
                    <img src="/dai_modest/medias/logo.png" class="logo-img" alt="LOGO">
                    
                    <span class="logo-span">戴某的博客</span>
                </a>
            </div>
            

<a href="#" data-target="mobile-nav" class="sidenav-trigger button-collapse"><i class="fas fa-bars"></i></a>
<ul class="right nav-menu">
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/dai_modest/" class="waves-effect waves-light">
      
      <i class="fas fa-home" style="zoom: 0.6;"></i>
      
      <span>首页</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/dai_modest/tags" class="waves-effect waves-light">
      
      <i class="fas fa-tags" style="zoom: 0.6;"></i>
      
      <span>标签</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/dai_modest/categories" class="waves-effect waves-light">
      
      <i class="fas fa-bookmark" style="zoom: 0.6;"></i>
      
      <span>分类</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/dai_modest/archives" class="waves-effect waves-light">
      
      <i class="fas fa-archive" style="zoom: 0.6;"></i>
      
      <span>归档</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/dai_modest/about" class="waves-effect waves-light">
      
      <i class="fas fa-user-circle" style="zoom: 0.6;"></i>
      
      <span>关于</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/dai_modest/contact" class="waves-effect waves-light">
      
      <i class="fas fa-comments" style="zoom: 0.6;"></i>
      
      <span>留言板</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/dai_modest/friends" class="waves-effect waves-light">
      
      <i class="fas fa-address-book" style="zoom: 0.6;"></i>
      
      <span>友情链接</span>
    </a>
    
  </li>
  
  <li>
    <a href="#searchModal" class="modal-trigger waves-effect waves-light">
      <i id="searchIcon" class="fas fa-search" title="搜索" style="zoom: 0.85;"></i>
    </a>
  </li>
</ul>


<div id="mobile-nav" class="side-nav sidenav">

    <div class="mobile-head bg-color">
        
        <img src="/dai_modest/medias/logo.png" class="logo-img circle responsive-img">
        
        <div class="logo-name">戴某的博客</div>
        <div class="logo-desc">
            
            戴某的笔记
            
        </div>
    </div>

    

    <ul class="menu-list mobile-menu-list">
        
        <li class="m-nav-item">
	  
		<a href="/dai_modest/" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-home"></i>
			
			首页
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/dai_modest/tags" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-tags"></i>
			
			标签
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/dai_modest/categories" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-bookmark"></i>
			
			分类
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/dai_modest/archives" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-archive"></i>
			
			归档
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/dai_modest/about" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-user-circle"></i>
			
			关于
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/dai_modest/contact" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-comments"></i>
			
			留言板
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/dai_modest/friends" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-address-book"></i>
			
			友情链接
		</a>
          
        </li>
        
        
        <li><div class="divider"></div></li>
        <li>
            <a href="https://github.com/blinkfox/hexo-theme-matery" class="waves-effect waves-light" target="_blank">
                <i class="fab fa-github-square fa-fw"></i>Fork Me
            </a>
        </li>
        
    </ul>
</div>


        </div>

        
            <style>
    .nav-transparent .github-corner {
        display: none !important;
    }

    .github-corner {
        position: absolute;
        z-index: 10;
        top: 0;
        right: 0;
        border: 0;
        transform: scale(1.1);
    }

    .github-corner svg {
        color: #0f9d58;
        fill: #fff;
        height: 64px;
        width: 64px;
    }

    .github-corner:hover .octo-arm {
        animation: a 0.56s ease-in-out;
    }

    .github-corner .octo-arm {
        animation: none;
    }

    @keyframes a {
        0%,
        to {
            transform: rotate(0);
        }
        20%,
        60% {
            transform: rotate(-25deg);
        }
        40%,
        80% {
            transform: rotate(10deg);
        }
    }
</style>

<a href="https://github.com/blinkfox/hexo-theme-matery" class="github-corner tooltipped hide-on-med-and-down" target="_blank"
   data-tooltip="Fork Me" data-position="left" data-delay="50">
    <svg viewBox="0 0 250 250" aria-hidden="true">
        <path d="M0,0 L115,115 L130,115 L142,142 L250,250 L250,0 Z"></path>
        <path d="M128.3,109.0 C113.8,99.7 119.0,89.6 119.0,89.6 C122.0,82.7 120.5,78.6 120.5,78.6 C119.2,72.0 123.4,76.3 123.4,76.3 C127.3,80.9 125.5,87.3 125.5,87.3 C122.9,97.6 130.6,101.9 134.4,103.2"
              fill="currentColor" style="transform-origin: 130px 106px;" class="octo-arm"></path>
        <path d="M115.0,115.0 C114.9,115.1 118.7,116.5 119.8,115.4 L133.7,101.6 C136.9,99.2 139.9,98.4 142.2,98.6 C133.8,88.0 127.5,74.4 143.8,58.0 C148.5,53.4 154.0,51.2 159.7,51.0 C160.3,49.4 163.2,43.6 171.4,40.1 C171.4,40.1 176.1,42.5 178.8,56.2 C183.1,58.6 187.2,61.8 190.9,65.4 C194.5,69.0 197.7,73.2 200.1,77.6 C213.8,80.2 216.3,84.9 216.3,84.9 C212.7,93.1 206.9,96.0 205.4,96.6 C205.1,102.4 203.0,107.8 198.3,112.5 C181.9,128.9 168.3,122.5 157.7,114.1 C157.9,116.9 156.7,120.9 152.7,124.9 L141.0,136.5 C139.8,137.7 141.6,141.9 141.8,141.8 Z"
              fill="currentColor" class="octo-body"></path>
    </svg>
</a>
        
    </nav>

</header>

    



<div class="bg-cover pd-header post-cover" style="background-image: url('/dai_modest/medias/featureimages/12.jpg')">
    <div class="container" style="right: 0px;left: 0px;">
        <div class="row">
            <div class="col s12 m12 l12">
                <div class="brand">
                    <h1 class="description center-align post-title">DDD领域层的一些设计规范</h1>
                </div>
            </div>
        </div>
    </div>
</div>




<main class="post-container content">

    
    <link rel="stylesheet" href="/dai_modest/libs/tocbot/tocbot.css">
<style>
    #articleContent h1::before,
    #articleContent h2::before,
    #articleContent h3::before,
    #articleContent h4::before,
    #articleContent h5::before,
    #articleContent h6::before {
        display: block;
        content: " ";
        height: 100px;
        margin-top: -100px;
        visibility: hidden;
    }

    #articleContent :focus {
        outline: none;
    }

    .toc-fixed {
        position: fixed;
        top: 64px;
    }

    .toc-widget {
        width: 345px;
        padding-left: 20px;
    }

    .toc-widget .toc-title {
        padding: 35px 0 15px 17px;
        font-size: 1.5rem;
        font-weight: bold;
        line-height: 1.5rem;
    }

    .toc-widget ol {
        padding: 0;
        list-style: none;
    }

    #toc-content {
        padding-bottom: 30px;
        overflow: auto;
    }

    #toc-content ol {
        padding-left: 10px;
    }

    #toc-content ol li {
        padding-left: 10px;
    }

    #toc-content .toc-link:hover {
        color: #42b983;
        font-weight: 700;
        text-decoration: underline;
    }

    #toc-content .toc-link::before {
        background-color: transparent;
        max-height: 25px;

        position: absolute;
        right: 23.5vw;
        display: block;
    }

    #toc-content .is-active-link {
        color: #42b983;
    }

    #floating-toc-btn {
        position: fixed;
        right: 15px;
        bottom: 76px;
        padding-top: 15px;
        margin-bottom: 0;
        z-index: 998;
    }

    #floating-toc-btn .btn-floating {
        width: 48px;
        height: 48px;
    }

    #floating-toc-btn .btn-floating i {
        line-height: 48px;
        font-size: 1.4rem;
    }
</style>
<div class="row">
    <div id="main-content" class="col s12 m12 l9">
        <!-- 文章内容详情 -->
<div id="artDetail">
    <div class="card">
        <div class="card-content article-info">
            <div class="row tag-cate">
                <div class="col s7">
                    
                    <div class="article-tag">
                        
                            <a href="/dai_modest/tags/java/">
                                <span class="chip bg-color">java</span>
                            </a>
                        
                    </div>
                    
                </div>
                <div class="col s5 right-align">
                    
                    <div class="post-cate">
                        <i class="fas fa-bookmark fa-fw icon-category"></i>
                        
                            <a href="/dai_modest/categories/%E4%B9%A6%E7%B1%8D%E7%B1%BB/" class="post-category">
                                书籍类
                            </a>
                        
                            <a href="/dai_modest/categories/%E4%B9%A6%E7%B1%8D%E7%B1%BB/%E7%AC%94%E8%AE%B0%E7%B1%BB/" class="post-category">
                                笔记类
                            </a>
                        
                            <a href="/dai_modest/categories/%E4%B9%A6%E7%B1%8D%E7%B1%BB/%E7%AC%94%E8%AE%B0%E7%B1%BB/%E3%80%8A%E9%A2%86%E5%9F%9F%E9%A9%B1%E5%8A%A8%E8%AE%BE%E8%AE%A1%E3%80%8B/" class="post-category">
                                《领域驱动设计》
                            </a>
                        
                    </div>
                    
                </div>
            </div>

            <div class="post-info">
                
                <div class="post-date info-break-policy">
                    <i class="far fa-calendar-minus fa-fw"></i>发布日期:&nbsp;&nbsp;
                    2023-03-01
                </div>
                

                
                <div class="post-date info-break-policy">
                    <i class="far fa-calendar-check fa-fw"></i>更新日期:&nbsp;&nbsp;
                    2023-03-09
                </div>
                

                
                <div class="info-break-policy">
                    <i class="far fa-file-word fa-fw"></i>文章字数:&nbsp;&nbsp;
                    3.2k
                </div>
                

                

                
            </div>
        </div>
        <hr class="clearfix">

        
        <!-- 是否加载使用自带的 prismjs. -->
        <link rel="stylesheet" href="/dai_modest/libs/prism/prism.css">
        

        
        <!-- 代码块折行 -->
        <style type="text/css">
            code[class*="language-"], pre[class*="language-"] { white-space: pre-wrap !important; }
        </style>
        

        <div class="card-content article-card-content">
            <div id="articleContent">
                <h2 id="DDD领域层的一些设计规范"><a href="#DDD领域层的一些设计规范" class="headerlink" title="DDD领域层的一些设计规范"></a><strong>DDD领域层的一些设计规范</strong></h2><h3 id="实体类（Entity）"><a href="#实体类（Entity）" class="headerlink" title="实体类（Entity）"></a>实体类（Entity）</h3><p>大多数DDD架构的核心都是实体类，实体类包含了一个领域里的状态、以及对状态的直接操作。Entity最重要的设计原则是保证实体的不变性（Invariants）。</p>
<p>核心：<em><strong>要确保无论外部怎么操作，一个实体内部的属性都不能出现相互冲突，状态不一致的情况</strong></em>。</p>
<p><strong>创建即一致</strong></p>
<p>在贫血模型里，通常见到的代码是一个模型通过手动new出来之后，由调用方一个参数一个参数的赋值，这就很容易产生遗漏，导致实体状态不一致。</p>
<p>然而在DDD里实体创建的方法有两种：<strong>constructor参数要包含所有必要属性，或者在constructor里有合理的默认值。</strong>如果缺少一个强校验的constructor，就无法保障创建的实体的一致性。所以需要增加一个强校验的constructor。可以使用Factory模式来降低调用方法的复杂度，比如<code>@Builder</code>来降低创建对象的复杂性。</p>
<p><strong>尽量避免public setter</strong></p>
<p>一个订单可能包含订单状态（下单、已支付、已发货、已收货）、支付单、物流单等子实体，如果一个调用方能随意去set订单状态，就有可能导致订单状态和子实体匹配不上，导致业务流程走不通的情况。所以在实体里，需要通过行为方法来修改内部状态。</p>
<p><strong>通过聚合根保证主子实体一致性</strong></p>
<p>在稍微复杂一点的领域里，通常主实体会包含子实体，这时候主实体就需要起到聚合根的作用（类似聚合根但不是）</p>
<pre class="line-numbers language-java" data-language="java"><code class="language-java">public class Spu &#123;
    private final ShopId shopId;
    private final String spuId;
    private final String supplierId;
    private final Sku sku;
&#125;
<span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre>

<p>就如上所示SPU里面包含SKU的子类。</p>
<p>对应标准：</p>
<pre class="line-numbers language-java" data-language="java"><code class="language-java">&#x2F;&#x2F;子实体标准
&#x2F;*
- 子实体不能单独存在，只能通过聚合根的方法获取到。任何外部的对象都不能直接保留子实体的引用
- 子实体没有独立的Repository，不可以单独保存和取出，必须要通过聚合根的Repository实例化
- 子实体可以单独修改自身状态，但是多个子实体之间的状态一致性需要聚合根来保障
*&#x2F;<span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre>



<p><strong>不可以强依赖其他聚合根实体或领域服务</strong></p>
<p>一个实体的原则是高内聚、低耦合，即一个实体类不能直接在内部直接一个外部的实体或服务。</p>
<p>因为如果对外部对象的依赖性会导致实体无法被单测，以及一个实体无法保证外部实体变更后不会影响本实体的一致性和正确性。</p>
<p>正确的外部依赖的方法有两种：</p>
<ul>
<li>只保存外部实体的ID：建议保存强类型的ID对象，而不是Long型的ID，强类型不单单能自我包含验证代码保证ID的正确性，还能保证入参因为参数顺序变化而出bug。类似于项目中MemberID。</li>
<li>正对”无副作用“的外部依赖，通过方法入参的方式传入。</li>
</ul>
<p><strong>任何实体的行为只能直接影响到本实体（和其子实体）</strong></p>
<p>这个原则更多的确保代码可读性、可理解性的原则，即任何实体的行为不能有直接的副作用，即直接修改其他的实体。</p>
<h3 id="领域服务（Domain-Service）"><a href="#领域服务（Domain-Service）" class="headerlink" title="领域服务（Domain Service）"></a>领域服务（Domain Service）</h3><p><strong>单对象策略型</strong></p>
<p>实体应该通过方法入参的方式传入这种领域服务，然后通过Double DIspatch来反转调用领域服务的方法。</p>
<pre class="line-numbers language-java" data-language="java"><code class="language-java">Player.equip(Weapon, EquipmentService) &#123;
    EquipmentService.canEquip(this, Weapon);
&#125;<span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span></span></code></pre>



<p><strong>跨对象事务型</strong></p>
<p>当一个行为会直接修改多个实体时，不能再通过单一实体的方法作处理，而必须直接使用领域服务的方法来做操作。在这里，领域服务更多的起到了跨对象事务的作用，确保多个实体的变更之间是有一致性的。</p>
<pre class="line-numbers language-java" data-language="java"><code class="language-java">
public class Player &#123;
    void attack(Monster, CombatService) &#123;
        CombatService.performAttack(this, Monster); &#x2F;&#x2F; ❌，不要这么写，会导致副作用
    &#125;
&#125;

&#x2F;&#x2F;正确写法

public void test() &#123;
    &#x2F;&#x2F;...
    combatService.performAttack(mage, orc);
&#125;<span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre>

<p>即Player.attack会直接影响到Monster，但这个调用Monster又没有感知。如果在使用类中写，那么Monster就会有感知。</p>
<p><strong>通用组件型</strong></p>
<p>这种类型的领域服务更像ECS里的System，提供了组件化的行为，但本身又不直接绑死在一种实体类上。</p>
<h2 id="策略对象（Domain-Policy）"><a href="#策略对象（Domain-Policy）" class="headerlink" title="策略对象（Domain Policy）"></a>策略对象（Domain Policy）</h2><p>Policy或者Strategy设计模式是一个通用的设计模式，但是在DDD架构中会经常出现，其核心就是封装领域规则。</p>
<p>一个Policy是一个无状态的单例对象，通常需要至少2个方法：canApply 和 一个业务方法。其中，canApply方法用来判断一个Policy是否适用于当前的上下文，如果适用则调用方会去触发业务方法。通常，为了降低一个Policy的可测试性和复杂度，Policy不应该直接操作对象，而是通过返回计算后的值，在Domain Service里对对象进行操作。</p>
<p>类似于项目中的是否创建订单那些操作。</p>
<pre class="line-numbers language-java" data-language="java"><code class="language-java">public void close() &#123;
    if (this.orderStatus.toEnum().isAllowClose()) &#123;
        this.orderStatus &#x3D; OrderStatus.of(OrderStatus.State.CLOSED);
        OrderClosedEvent event &#x3D; new OrderClosedEvent(this);
        this.register(event);
    &#125;
    throw new IllegalStateException(&quot;当前状态无法关闭交易&quot;);
&#125;<span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre>





<h2 id="领域事件"><a href="#领域事件" class="headerlink" title="领域事件"></a>领域事件</h2><p>领域事件是一个在领域里发生了某些事后，希望领域里其他对象能够感知到的通知机制。领域事件的好处就是将这种隐性的副作用“显性化”，通过一个显性的事件，将事件触发和事件处理解耦，最终起到代码更清晰、扩展性更好的目的。（不需要每次一改变触发条件就修改代码）。</p>
<p>所以，领域事件是在DDD里，比较推荐使用的跨实体“副作用”传播机制。</p>
<p>因为Entity不能直接依赖外部对象，所以EventBus目前之恶能是一个全局的Singleton。而且全局的Singletion是很难被单测的，所以就容易导致Entity对象无法很容易的被完整覆盖全。</p>
<p>所以有一种解法就是对于每一个聚合增加一个list来存放事件。</p>
<pre class="line-numbers language-java" data-language="java"><code class="language-java">@SuperBuilder
public abstract class AggregateRoot &#123;
    private final String id;
    private final transient List&lt;DomainEventStandard&gt; domainEvents &#x3D; new ArrayList&lt;&gt;();
&#125;
<span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span></span></code></pre>



<h2 id="正确代码格式"><a href="#正确代码格式" class="headerlink" title="正确代码格式"></a>正确代码格式</h2><ul>
<li><p>分离出独立的Interface接口层，负责处理网络协议相关的逻辑</p>
</li>
<li><p>从真实业务场景中，找出具体用例（Use Cases），然后将具体用例通过专用的Command指令、Query查询、和Event事件对象来承接</p>
</li>
<li><p>分离出独立的Application应用层，负责业务流程的编排，响应Command、Query和Event。每个应用层的方法应该代表整个业务流程中的一个节点</p>
</li>
<li><p>处理一些跨层的横切关注点，如鉴权、异常处理、校验、缓存、日志等</p>
</li>
</ul>
<pre class="line-numbers language-java" data-language="java"><code class="language-java">规范：Interface层的HTTP和RPC接口，返回值为Result，捕捉所有异常
规范：Application层的所有接口返回值为DTO，不负责处理异常<span aria-hidden="true" class="line-numbers-rows"><span></span><span></span></span></code></pre>



<h3 id="Interface接口层"><a href="#Interface接口层" class="headerlink" title="Interface接口层"></a>Interface接口层</h3><p>在DDD的分层架构中，我们单独会抽取出来Interface接口层，作为所有对外的门户，将网络协议和业务逻辑解耦。</p>
<p>Interface层的每一个接口都要写异常处理逻辑，所以会比较麻烦，我们可以使用AOP做一个注解然后统一异常处理。项目中使用的是在每个接口的时候使用日志，在日志进行判断是否异常，然后统一做异常处理。</p>
<pre class="line-numbers language-java" data-language="java"><code class="language-java">规范：一个Interface层的类应该是“小而美”的，应该是面向“一个单一的业务”或“一类同样需求的业务”，需要尽量避免用同一个类承接不同类型业务的需求。<span aria-hidden="true" class="line-numbers-rows"><span></span></span></code></pre>

<p>。<strong>一个建议是当一个现有的接口类过度膨胀时，可以考虑对接口类做拆分，拆分原则和SRP一致。</strong></p>
<p><img src="D:\MyConfiguration\wenlin.dai\AppData\Roaming\Typora\typora-user-images\image-20220711180446864.png" alt="image-20220711180446864"></p>
<p>在DDD分层架构中，接口类的核心作用仅仅是协议层，而真实的业务逻辑会沉淀到应用层，也就是说Interface和Application的关系是多对多的。</p>
<h2 id="Application层"><a href="#Application层" class="headerlink" title="Application层"></a>Application层</h2><p>Application层的作用就是胶水，黏合其他层。</p>
<ul>
<li>ApplicationService应用服务：最核心的类，负责业务流程的编排，但本身不负责任何业务逻辑</li>
<li>DTO Assembler：负责将内部领域模型转化为可对外的DTO</li>
<li>Command、Query、Event对象：作为ApplicationService的入参</li>
<li>返回的DTO：作为ApplicationService的出参</li>
</ul>
<h3 id="Command、Query、Event对象"><a href="#Command、Query、Event对象" class="headerlink" title="Command、Query、Event对象"></a>Command、Query、Event对象</h3><p>Command指令：指调用方明确想让系统操作的指令，其预期是对一个系统有影响，也就是写操作。通常来讲指令需要有一个明确的返回值（如同步的操作结果，或异步的指令已经被接受）。</p>
<p>Query查询：指调用方明确想查询的东西，包括查询参数、过滤、分页等条件，其预期是对一个系统的数据完全不影响的，也就是只读操作。</p>
<p>Event事件：指一件已经发生过的既有事实，需要系统根据这个事实作出改变或者响应的，通常事件处理都会有一定的写操作。事件处理器不会有返回值。这里需要注意一下的是，Application层的Event概念和Domain层的DomainEvent是类似的概念，但不一定是同一回事，这里的Event更多是外部一种通知机制而已。</p>
<p>规范：ApplicationService的接口入参只能是一个Command、Query或Event对象，CQE对象需要能代表当前方法的语意。唯一可以的例外是根据单一ID查询的情况，可以省略掉一个Query对象的创建。</p>
<p>CQE和DTO的区别：</p>
<p>CQE：CQE对象是ApplicationService的输入，是有明确的”意图“的，所以这个对象必须保证其”正确性“。</p>
<p>DTO：DTO对象只是数据容器，只是为了和外部交互，所以本身不包含任何逻辑，只是贫血对象。</p>
<p><strong>避免复用CQE</strong></p>
<p>因为CQE是有“意图”和“语意”的，我们需要尽量避免CQE对象的复用，哪怕所有的参数都一样，只要他们的语意不同，尽量还是要用不同的对象。</p>
<p>规范：针对于不同语意的指令，要避免CQE对象的复用</p>
<p><strong>Application Service 是业务流程的封装，不处理业务逻辑</strong></p>
<p>不要有if/else分支逻辑：也就是说代码的Cyclomatic Complexity（循环复杂度）应该尽量等于1，虽然CC &gt; 1，但是仅仅代表了中断条件，具体的业务逻辑处理并没有受影响。</p>
<p>我们可以看出来，ApplicationService的代码通常有类似的结构：AppService通常不做任何决策（Precondition除外），仅仅是把所有决策交给DomainService或Entity，把跟外部交互的交给Infrastructure接口，如Repository或防腐层。</p>
<p><strong>规范ApplicationService应该永远返回DTO而不是Entity</strong></p>
<ul>
<li><p>构建领域边界：ApplicationService的入参是CQE对象，出参是DTO，这些基本上都属于简单的POJO，来确保Application层的内外互相不影响。</p>
</li>
<li><p>降低规则依赖：Entity里面通常会包含业务规则，如果ApplicationService返回Entity，则会导致调用方直接依赖业务规则。如果内部规则变更可能直接影响到外部。</p>
</li>
<li><p>通过DTO组合降低成本：Entity是有限的，DTO可以是多个Entity、VO的自由组合，一次性封装成复杂DTO，或者有选择的抽取部分参数封装成DTO可以降低对外的成本。</p>
</li>
</ul>
<p>简化操作使用MapStruct</p>
<pre class="line-numbers language-java" data-language="java"><code class="language-java">import org.mapstruct.Mapper;
@Mapper
public interface OrderDtoAssembler &#123;
    OrderDtoAssembler INSTANCE &#x3D; Mappers.getMapper(OrderDtoAssembler.class);
    OrderDTO orderToDTO(Order order);
&#125;
public class CheckoutServiceImpl implements CheckoutService &#123;
    private final OrderDtoAssembler orderDtoAssembler &#x3D; OrderDtoAssembler.INSTANCE;
    @Override
    public OrderDTO checkout(@Valid CheckoutCommand cmd) &#123;
        &#x2F;&#x2F; ...
          Order order &#x3D; new Order();    
        &#x2F;&#x2F; ...
        Order savedOrder &#x3D; orderRepository.save(order);
        return orderDtoAssembler.orderToDTO(savedOrder);
    &#125;
&#125;<span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre>

<p><img src="D:\MyConfiguration\wenlin.dai\AppData\Roaming\Typora\typora-user-images\image-20220711195353705.png" alt="image-20220711195353705"></p>
<h2 id="防腐层"><a href="#防腐层" class="headerlink" title="防腐层"></a>防腐层</h2><p>会发现我们的ApplicationService会强依赖ItemService、InventoryService以及ItemDO这个对象。如果任何一个服务的方法变更，或者ItemDO字段变更，都会有可能影响到ApplicationService的代码。也就是说，我们自己的代码会因为强依赖了外部系统的变化而变更，这个在复杂系统中应该是尽量避免的。那么如何做到对外部系统的隔离呢？需要加入ACL防腐层。</p>
<ul>
<li><p>对于依赖的外部对象，我们抽取出所需要的字段，生成一个内部所需的VO或DTO类</p>
</li>
<li><p>构建一个新的Facade，在Facade中封装调用链路，将外部类转化为内部类</p>
</li>
<li><p>针对外部系统调用，同样的用Facade方法封装外部调用链路</p>
</li>
</ul>

                
            </div>
            <hr/>

            

    <div class="reprint" id="reprint-statement">
        
            <div class="reprint__author">
                <span class="reprint-meta" style="font-weight: bold;">
                    <i class="fas fa-user">
                        文章作者:
                    </i>
                </span>
                <span class="reprint-info">
                    <a href="/dai_modest/about" rel="external nofollow noreferrer">戴某人</a>
                </span>
            </div>
            <div class="reprint__type">
                <span class="reprint-meta" style="font-weight: bold;">
                    <i class="fas fa-link">
                        文章链接:
                    </i>
                </span>
                <span class="reprint-info">
                    <a href="https://modest2001.gitee.io/dai_modest/dai_modest/2023/03/01/ddd-ling-yu-ceng-de-she-ji-gui-fan/">https://modest2001.gitee.io/dai_modest/dai_modest/2023/03/01/ddd-ling-yu-ceng-de-she-ji-gui-fan/</a>
                </span>
            </div>
            <div class="reprint__notice">
                <span class="reprint-meta" style="font-weight: bold;">
                    <i class="fas fa-copyright">
                        版权声明:
                    </i>
                </span>
                <span class="reprint-info">
                    本博客所有文章除特別声明外，均采用
                    <a href="https://creativecommons.org/licenses/by/4.0/deed.zh" rel="external nofollow noreferrer" target="_blank">CC BY 4.0</a>
                    许可协议。转载请注明来源
                    <a href="/dai_modest/about" target="_blank">戴某人</a>
                    !
                </span>
            </div>
        
    </div>

    <script async defer>
      document.addEventListener("copy", function (e) {
        let toastHTML = '<span>复制成功，请遵循本文的转载规则</span><button class="btn-flat toast-action" onclick="navToReprintStatement()" style="font-size: smaller">查看</a>';
        M.toast({html: toastHTML})
      });

      function navToReprintStatement() {
        $("html, body").animate({scrollTop: $("#reprint-statement").offset().top - 80}, 800);
      }
    </script>



            <div class="tag_share" style="display: block;">
                <div class="post-meta__tag-list" style="display: inline-block;">
                    
                        <div class="article-tag">
                            
                                <a href="/dai_modest/tags/java/">
                                    <span class="chip bg-color">java</span>
                                </a>
                            
                        </div>
                    
                </div>
                <div class="post_share" style="zoom: 80%; width: fit-content; display: inline-block; float: right; margin: -0.15rem 0;">
                    <link rel="stylesheet" type="text/css" href="/dai_modest/libs/share/css/share.min.css">
<div id="article-share">

    
    <div class="social-share" data-sites="twitter,facebook,google,qq,qzone,wechat,weibo,douban,linkedin" data-wechat-qrcode-helper="<p>微信扫一扫即可分享！</p>"></div>
    <script src="/dai_modest/libs/share/js/social-share.min.js"></script>
    

    
    <script type="text/javascript" src="//s7.addthis.com/js/300/addthis_widget.js#pubid="></script>
    <div class="addthis_inline_share_toolbox"></div>
    

</div>

                </div>
            </div>
            
                <style>
    #reward {
        margin: 40px 0;
        text-align: center;
    }

    #reward .reward-link {
        font-size: 1.4rem;
        line-height: 38px;
    }

    #reward .btn-floating:hover {
        box-shadow: 0 6px 12px rgba(0, 0, 0, 0.2), 0 5px 15px rgba(0, 0, 0, 0.2);
    }

    #rewardModal {
        width: 320px;
        height: 350px;
    }

    #rewardModal .reward-title {
        margin: 15px auto;
        padding-bottom: 5px;
    }

    #rewardModal .modal-content {
        padding: 10px;
    }

    #rewardModal .close {
        position: absolute;
        right: 15px;
        top: 15px;
        color: rgba(0, 0, 0, 0.5);
        font-size: 1.3rem;
        line-height: 20px;
        cursor: pointer;
    }

    #rewardModal .close:hover {
        color: #ef5350;
        transform: scale(1.3);
        -moz-transform:scale(1.3);
        -webkit-transform:scale(1.3);
        -o-transform:scale(1.3);
    }

    #rewardModal .reward-tabs {
        margin: 0 auto;
        width: 210px;
    }

    .reward-tabs .tabs {
        height: 38px;
        margin: 10px auto;
        padding-left: 0;
    }

    .reward-content ul {
        padding-left: 0 !important;
    }

    .reward-tabs .tabs .tab {
        height: 38px;
        line-height: 38px;
    }

    .reward-tabs .tab a {
        color: #fff;
        background-color: #ccc;
    }

    .reward-tabs .tab a:hover {
        background-color: #ccc;
        color: #fff;
    }

    .reward-tabs .wechat-tab .active {
        color: #fff !important;
        background-color: #22AB38 !important;
    }

    .reward-tabs .alipay-tab .active {
        color: #fff !important;
        background-color: #019FE8 !important;
    }

    .reward-tabs .reward-img {
        width: 210px;
        height: 210px;
    }
</style>

<div id="reward">
    <a href="#rewardModal" class="reward-link modal-trigger btn-floating btn-medium waves-effect waves-light red">赏</a>

    <!-- Modal Structure -->
    <div id="rewardModal" class="modal">
        <div class="modal-content">
            <a class="close modal-close"><i class="fas fa-times"></i></a>
            <h4 class="reward-title">你的赏识是我前进的动力</h4>
            <div class="reward-content">
                <div class="reward-tabs">
                    <ul class="tabs row">
                        <li class="tab col s6 alipay-tab waves-effect waves-light"><a href="#alipay">支付宝</a></li>
                        <li class="tab col s6 wechat-tab waves-effect waves-light"><a href="#wechat">微 信</a></li>
                    </ul>
                    <div id="alipay">
                        <img src="/dai_modest/medias/reward/alipay.jpg" class="reward-img" alt="支付宝打赏二维码">
                    </div>
                    <div id="wechat">
                        <img src="/dai_modest/medias/reward/wechat.png" class="reward-img" alt="微信打赏二维码">
                    </div>
                </div>
            </div>
        </div>
    </div>
</div>

<script>
    $(function () {
        $('.tabs').tabs();
    });
</script>

            
        </div>
    </div>

    

    

    

    

    

    

    

    

    

<article id="prenext-posts" class="prev-next articles">
    <div class="row article-row">
        
        <div class="article col s12 m6" data-aos="fade-up">
            <div class="article-badge left-badge text-color">
                <i class="fas fa-chevron-left"></i>&nbsp;上一篇</div>
            <div class="card">
                <a href="/dai_modest/2023/03/01/java-xing-neng-diao-you-shi-zhan-ji-ke-bi-ji/">
                    <div class="card-image">
                        
                        
                        <img src="/dai_modest/medias/featureimages/9.jpg" class="responsive-img" alt="java性能调优实战">
                        
                        <span class="card-title">java性能调优实战</span>
                    </div>
                </a>
                <div class="card-content article-content">
                    <div class="summary block-with-text">
                        
                            java性能调优实战
                        
                    </div>
                    <div class="publish-info">
                        <span class="publish-date">
                            <i class="far fa-clock fa-fw icon-date"></i>2023-03-01
                        </span>
                        <span class="publish-author">
                            
                            <i class="fas fa-bookmark fa-fw icon-category"></i>
                            
                            <a href="/dai_modest/categories/%E4%B9%A6%E7%B1%8D/" class="post-category">
                                    书籍
                                </a>
                            
                            <a href="/dai_modest/categories/%E4%B9%A6%E7%B1%8D/%E7%AC%94%E8%AE%B0%E7%B1%BB/" class="post-category">
                                    笔记类
                                </a>
                            
                            <a href="/dai_modest/categories/%E4%B9%A6%E7%B1%8D/%E7%AC%94%E8%AE%B0%E7%B1%BB/%E3%80%8Ajava%E6%80%A7%E8%83%BD%E8%B0%83%E4%BC%98%E5%AE%9E%E6%88%98%E3%80%8B/" class="post-category">
                                    《java性能调优实战》
                                </a>
                            
                            
                        </span>
                    </div>
                </div>
                
                <div class="card-action article-tags">
                    
                    <a href="/dai_modest/tags/java/">
                        <span class="chip bg-color">java</span>
                    </a>
                    
                </div>
                
            </div>
        </div>
        
        
        <div class="article col s12 m6" data-aos="fade-up">
            <div class="article-badge right-badge text-color">
                下一篇&nbsp;<i class="fas fa-chevron-right"></i>
            </div>
            <div class="card">
                <a href="/dai_modest/2023/03/01/cqrs-jian-shu/">
                    <div class="card-image">
                        
                        
                        <img src="/dai_modest/medias/featureimages/13.jpg" class="responsive-img" alt="CQRS架构概述">
                        
                        <span class="card-title">CQRS架构概述</span>
                    </div>
                </a>
                <div class="card-content article-content">
                    <div class="summary block-with-text">
                        
                            CQRS架构概述
                        
                    </div>
                    <div class="publish-info">
                            <span class="publish-date">
                                <i class="far fa-clock fa-fw icon-date"></i>2023-03-01
                            </span>
                        <span class="publish-author">
                            
                            <i class="fas fa-bookmark fa-fw icon-category"></i>
                            
                            <a href="/dai_modest/categories/%E9%A1%B9%E7%9B%AE%E7%B1%BB/" class="post-category">
                                    项目类
                                </a>
                            
                            <a href="/dai_modest/categories/%E9%A1%B9%E7%9B%AE%E7%B1%BB/%E7%AC%94%E8%AE%B0%E7%B1%BB/" class="post-category">
                                    笔记类
                                </a>
                            
                            
                        </span>
                    </div>
                </div>
                
                <div class="card-action article-tags">
                    
                    <a href="/dai_modest/tags/java/">
                        <span class="chip bg-color">java</span>
                    </a>
                    
                    <a href="/dai_modest/tags/%E5%BE%AE%E6%9C%8D%E5%8A%A1/">
                        <span class="chip bg-color">微服务</span>
                    </a>
                    
                    <a href="/dai_modest/tags/CQRS/">
                        <span class="chip bg-color">CQRS</span>
                    </a>
                    
                </div>
                
            </div>
        </div>
        
    </div>
</article>

</div>


<script>
    $('#articleContent').on('copy', function (e) {
        // IE8 or earlier browser is 'undefined'
        if (typeof window.getSelection === 'undefined') return;

        var selection = window.getSelection();
        // if the selection is short let's not annoy our users.
        if (('' + selection).length < Number.parseInt('120')) {
            return;
        }

        // create a div outside of the visible area and fill it with the selected text.
        var bodyElement = document.getElementsByTagName('body')[0];
        var newdiv = document.createElement('div');
        newdiv.style.position = 'absolute';
        newdiv.style.left = '-99999px';
        bodyElement.appendChild(newdiv);
        newdiv.appendChild(selection.getRangeAt(0).cloneContents());

        // we need a <pre> tag workaround.
        // otherwise the text inside "pre" loses all the line breaks!
        if (selection.getRangeAt(0).commonAncestorContainer.nodeName === 'PRE' || selection.getRangeAt(0).commonAncestorContainer.nodeName === 'CODE') {
            newdiv.innerHTML = "<pre>" + newdiv.innerHTML + "</pre>";
        }

        var url = document.location.href;
        newdiv.innerHTML += '<br />'
            + '来源: 戴某的博客<br />'
            + '文章作者: 戴某人<br />'
            + '文章链接: <a href="' + url + '">' + url + '</a><br />'
            + '本文章著作权归作者：戴某人所有，任何形式的转载都请注明出处。';

        selection.selectAllChildren(newdiv);
        window.setTimeout(function () {bodyElement.removeChild(newdiv);}, 200);
    });
</script>


<!-- 代码块功能依赖 -->
<script type="text/javascript" src="/dai_modest/libs/codeBlock/codeBlockFuction.js"></script>

<!-- 代码语言 -->

<script type="text/javascript" src="/dai_modest/libs/codeBlock/codeLang.js"></script>


<!-- 代码块复制 -->

<script type="text/javascript" src="/dai_modest/libs/codeBlock/codeCopy.js"></script>


<!-- 代码块收缩 -->

<script type="text/javascript" src="/dai_modest/libs/codeBlock/codeShrink.js"></script>


    </div>
    <div id="toc-aside" class="expanded col l3 hide-on-med-and-down">
        <div class="toc-widget card" style="background-color: white;">
            <div class="toc-title"><i class="far fa-list-alt"></i>&nbsp;&nbsp;目录</div>
            <div id="toc-content"></div>
        </div>
    </div>
</div>

<!-- TOC 悬浮按钮. -->

<div id="floating-toc-btn" class="hide-on-med-and-down">
    <a class="btn-floating btn-large bg-color">
        <i class="fas fa-list-ul"></i>
    </a>
</div>


<script src="/dai_modest/libs/tocbot/tocbot.min.js"></script>
<script>
    $(function () {
        tocbot.init({
            tocSelector: '#toc-content',
            contentSelector: '#articleContent',
            headingsOffset: -($(window).height() * 0.4 - 45),
            collapseDepth: Number('0'),
            headingSelector: 'h2, h3, h4'
        });

        // modify the toc link href to support Chinese.
        let i = 0;
        let tocHeading = 'toc-heading-';
        $('#toc-content a').each(function () {
            $(this).attr('href', '#' + tocHeading + (++i));
        });

        // modify the heading title id to support Chinese.
        i = 0;
        $('#articleContent').children('h2, h3, h4').each(function () {
            $(this).attr('id', tocHeading + (++i));
        });

        // Set scroll toc fixed.
        let tocHeight = parseInt($(window).height() * 0.4 - 64);
        let $tocWidget = $('.toc-widget');
        $(window).scroll(function () {
            let scroll = $(window).scrollTop();
            /* add post toc fixed. */
            if (scroll > tocHeight) {
                $tocWidget.addClass('toc-fixed');
            } else {
                $tocWidget.removeClass('toc-fixed');
            }
        });

        
        /* 修复文章卡片 div 的宽度. */
        let fixPostCardWidth = function (srcId, targetId) {
            let srcDiv = $('#' + srcId);
            if (srcDiv.length === 0) {
                return;
            }

            let w = srcDiv.width();
            if (w >= 450) {
                w = w + 21;
            } else if (w >= 350 && w < 450) {
                w = w + 18;
            } else if (w >= 300 && w < 350) {
                w = w + 16;
            } else {
                w = w + 14;
            }
            $('#' + targetId).width(w);
        };

        // 切换TOC目录展开收缩的相关操作.
        const expandedClass = 'expanded';
        let $tocAside = $('#toc-aside');
        let $mainContent = $('#main-content');
        $('#floating-toc-btn .btn-floating').click(function () {
            if ($tocAside.hasClass(expandedClass)) {
                $tocAside.removeClass(expandedClass).hide();
                $mainContent.removeClass('l9');
            } else {
                $tocAside.addClass(expandedClass).show();
                $mainContent.addClass('l9');
            }
            fixPostCardWidth('artDetail', 'prenext-posts');
        });
        
    });
</script>

    

</main>




    <footer class="page-footer bg-color">
    
        <link rel="stylesheet" href="/dai_modest/libs/aplayer/APlayer.min.css">
<style>
    .aplayer .aplayer-lrc p {
        
        display: none;
        
        font-size: 12px;
        font-weight: 700;
        line-height: 16px !important;
    }

    .aplayer .aplayer-lrc p.aplayer-lrc-current {
        
        display: none;
        
        font-size: 15px;
        color: #42b983;
    }

    
    .aplayer.aplayer-fixed.aplayer-narrow .aplayer-body {
        left: -66px !important;
    }

    .aplayer.aplayer-fixed.aplayer-narrow .aplayer-body:hover {
        left: 0px !important;
    }

    
</style>
<div class="">
    
    <div class="row">
        <meting-js class="col l8 offset-l2 m10 offset-m1 s12"
                   server="netease"
                   type="playlist"
                   id="503838841"
                   fixed='true'
                   autoplay='false'
                   theme='#42b983'
                   loop='all'
                   order='random'
                   preload='auto'
                   volume='0.7'
                   list-folded='true'
        >
        </meting-js>
    </div>
</div>

<script src="/dai_modest/libs/aplayer/APlayer.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/meting@2/dist/Meting.min.js"></script>

    

    <div class="container row center-align"
         style="margin-bottom: 0px !important;">
        <div class="col s12 m8 l8 copy-right">
            Copyright&nbsp;&copy;
            
                <span id="year">2019-2023</span>
            
            <span id="year">2019</span>
            <a href="/dai_modest/about" target="_blank">戴某人</a>
            |&nbsp;Powered by&nbsp;<a href="https://hexo.io/" target="_blank">Hexo</a>
            |&nbsp;Theme&nbsp;<a href="https://github.com/blinkfox/hexo-theme-matery" target="_blank">Matery</a>
            <br>
            
                &nbsp;<i class="fas fa-chart-area"></i>&nbsp;站点总字数:&nbsp;<span
                        class="white-color">128.1k</span>
            
            
            
                
            
            
                <span id="busuanzi_container_site_pv">
                &nbsp;|&nbsp;<i class="far fa-eye"></i>&nbsp;总访问量:&nbsp;
                    <span id="busuanzi_value_site_pv" class="white-color"></span>
            </span>
            
            
                <span id="busuanzi_container_site_uv">
                &nbsp;|&nbsp;<i class="fas fa-users"></i>&nbsp;总访问人数:&nbsp;
                    <span id="busuanzi_value_site_uv" class="white-color"></span>
            </span>
            
            <br>

            <!-- 运行天数提醒. -->
            
            <br>
            
        </div>
        <div class="col s12 m4 l4 social-link social-statis">


    <a href="mailto:861796830@qq.com" class="tooltipped" target="_blank" data-tooltip="邮件联系我" data-position="top" data-delay="50">
        <i class="fas fa-envelope-open"></i>
    </a>







    <a href="tencent://AddContact/?fromId=50&fromSubId=1&subcmd=all&uin=861796830" class="tooltipped" target="_blank" data-tooltip="QQ联系我: 861796830" data-position="top" data-delay="50">
        <i class="fab fa-qq"></i>
    </a>







    <a href="/dai_modest/atom.xml" class="tooltipped" target="_blank" data-tooltip="RSS 订阅" data-position="top" data-delay="50">
        <i class="fas fa-rss"></i>
    </a>

</div>
    </div>
</footer>

<div class="progress-bar"></div>


    <!-- 搜索遮罩框 -->
<div id="searchModal" class="modal">
    <div class="modal-content">
        <div class="search-header">
            <span class="title"><i class="fas fa-search"></i>&nbsp;&nbsp;搜索</span>
            <input type="search" id="searchInput" name="s" placeholder="请输入搜索的关键字"
                   class="search-input">
        </div>
        <div id="searchResult"></div>
    </div>
</div>

<script type="text/javascript">
$(function () {
    var searchFunc = function (path, search_id, content_id) {
        'use strict';
        $.ajax({
            url: path,
            dataType: "xml",
            success: function (xmlResponse) {
                // get the contents from search data
                var datas = $("entry", xmlResponse).map(function () {
                    return {
                        title: $("title", this).text(),
                        content: $("content", this).text(),
                        url: $("url", this).text()
                    };
                }).get();
                var $input = document.getElementById(search_id);
                var $resultContent = document.getElementById(content_id);
                $input.addEventListener('input', function () {
                    var str = '<ul class=\"search-result-list\">';
                    var keywords = this.value.trim().toLowerCase().split(/[\s\-]+/);
                    $resultContent.innerHTML = "";
                    if (this.value.trim().length <= 0) {
                        return;
                    }
                    // perform local searching
                    datas.forEach(function (data) {
                        var isMatch = true;
                        var data_title = data.title.trim().toLowerCase();
                        var data_content = data.content.trim().replace(/<[^>]+>/g, "").toLowerCase();
                        var data_url = data.url;
                        data_url = data_url.indexOf('/') === 0 ? data.url : '/' + data_url;
                        var index_title = -1;
                        var index_content = -1;
                        var first_occur = -1;
                        // only match artiles with not empty titles and contents
                        if (data_title !== '' && data_content !== '') {
                            keywords.forEach(function (keyword, i) {
                                index_title = data_title.indexOf(keyword);
                                index_content = data_content.indexOf(keyword);
                                if (index_title < 0 && index_content < 0) {
                                    isMatch = false;
                                } else {
                                    if (index_content < 0) {
                                        index_content = 0;
                                    }
                                    if (i === 0) {
                                        first_occur = index_content;
                                    }
                                }
                            });
                        }
                        // show search results
                        if (isMatch) {
                            str += "<li><a href='" + data_url + "' class='search-result-title'>" + data_title + "</a>";
                            var content = data.content.trim().replace(/<[^>]+>/g, "");
                            if (first_occur >= 0) {
                                // cut out 100 characters
                                var start = first_occur - 20;
                                var end = first_occur + 80;
                                if (start < 0) {
                                    start = 0;
                                }
                                if (start === 0) {
                                    end = 100;
                                }
                                if (end > content.length) {
                                    end = content.length;
                                }
                                var match_content = content.substr(start, end);
                                // highlight all keywords
                                keywords.forEach(function (keyword) {
                                    var regS = new RegExp(keyword, "gi");
                                    match_content = match_content.replace(regS, "<em class=\"search-keyword\">" + keyword + "</em>");
                                });

                                str += "<p class=\"search-result\">" + match_content + "...</p>"
                            }
                            str += "</li>";
                        }
                    });
                    str += "</ul>";
                    $resultContent.innerHTML = str;
                });
            }
        });
    };

    searchFunc('/dai_modest/search.xml', 'searchInput', 'searchResult');
});
</script>

    <!-- 回到顶部按钮 -->
<div id="backTop" class="top-scroll">
    <a class="btn-floating btn-large waves-effect waves-light" href="#!">
        <i class="fas fa-arrow-up"></i>
    </a>
</div>


    <script src="/dai_modest/libs/materialize/materialize.min.js"></script>
    <script src="/dai_modest/libs/masonry/masonry.pkgd.min.js"></script>
    <script src="/dai_modest/libs/aos/aos.js"></script>
    <script src="/dai_modest/libs/scrollprogress/scrollProgress.min.js"></script>
    <script src="/dai_modest/libs/lightGallery/js/lightgallery-all.min.js"></script>
    <script src="/dai_modest/js/matery.js"></script>

    <!-- Baidu Analytics -->

    <!-- Baidu Push -->

<script>
    (function () {
        var bp = document.createElement('script');
        var curProtocol = window.location.protocol.split(':')[0];
        if (curProtocol === 'https') {
            bp.src = 'https://zz.bdstatic.com/linksubmit/push.js';
        } else {
            bp.src = 'http://push.zhanzhang.baidu.com/push.js';
        }
        var s = document.getElementsByTagName("script")[0];
        s.parentNode.insertBefore(bp, s);
    })();
</script>

    
    <script src="/dai_modest/libs/others/clicklove.js" async="async"></script>
    
    
    <script async src="/dai_modest/libs/others/busuanzi.pure.mini.js"></script>
    

    

    

    <!--腾讯兔小巢-->
    
        <div style="position:fixed;bottom:125px;right:16px;cursor: pointer;">
            <a title="兔小巢" target="_blank" rel="noopener" href="https://support.qq.com/products/"><i class="fa fa-comments fa-3x"  aria-hidden="true"></i></a>
        </div>
    
    
    <script type="text/javascript" color="0,0,255"
        pointColor="0,0,255" opacity='0.7'
        zIndex="-1" count="99"
        src="/dai_modest/libs/background/canvas-nest.js"></script>
    

    
    
    <script type="text/javascript" size="150" alpha='0.6'
        zIndex="-1" src="/dai_modest/libs/background/ribbon.min.js" async="async"></script>
    

    
    <script type="text/javascript" src="/dai_modest/libs/background/ribbon-dynamic.js" async="async"></script>
    

    
    <script src="/dai_modest/libs/instantpage/instantpage.js" type="module"></script>
    

<script src="/dai_modest/live2dw/lib/L2Dwidget.min.js?094cbace49a39548bed64abff5988b05"></script><script>L2Dwidget.init({"log":false,"pluginJsPath":"lib/","pluginModelPath":"assets/","pluginRootPath":"live2dw/","tagMode":false});</script></body>

</html>
